\documentclass{article}
\usepackage{fp}
\input pstfig
\begin{document}
\vspace*{3cm}
$
\def\myR{2.5}
\def\myr{1.8}
\def\myrate{3.5}
\def\myH{2.4}
\FPeval\myHH{round(\myH / (\myR - \myr) * \myR  : 4)}
\FPeval\myRr{round(\myR / \myrate : 4)}
\FPeval\myrr{round(\myr / \myrate : 4)}
\pnode(0,0){O}
\pnode(\myR, 0){A}
\pnode(-\myR, 0){B}
\pnode(\myr, \myH){C}
\pnode(-\myr, \myH){D}
\pnode(0, \myHH){S}
\pnode(0, \myH){P}
\psellipticarc(O)(\myR, \myRr){180}{0}
\psellipse(P)(\myr, \myrr)
\pcline(A)(C)
\pcline(B)(D)
\Aput{l}
\thinline\dashline
\psellipticarc(O)(\myR, \myRr){0}{180}
\psline(C)(S)(D)
\pcline(B)(O)
\nLput[offset=1.3ex](B)(O){0.6}{R_1}
\pcline(P)(O)
\Aput{H}
\solidline
\pcline(D)(P)
\nLput[offset=1.1ex](D)(P){0.8}{R_2}
$
\end{document}
